Diaphragm apparatus for burning gases.



W.A. BONE, J. W. WILSON & C. D. McCOURT.

DIAPHRAGM APPARATUS FOR BURNING GASES. APPLICATION FILED 5.20. 1912.RENEWED mm. 7. 1917. A

1,223,308. A Patented Apr. 17, 1917.

WITNESSES Q dNVEI/TORS ilhd '%:Ih -4hmr ATTORNEYS STATES PATENT oFFIoE.j

RTHUR DONE, or mains, JAMEs WILLIAM wILsoN, or ARMLRY', LEEDS, .AN'CYRIL ouGLAs MoCOUBT', OF LONDON, ENGLAND, AssIGNoRs To RADIANT HEATINGLIMITED, or LoNDoN, ENGL ND, A coRPoRATIoN or GREAT BRITAIN.

. DIAPHRAGM APPARATUS roR BURNIN GASES.

Speciflcation of Letters Patent. "Patented Apr. 17, 1917.

Original application filed October S, 1910, Serial No. 586,058. Dividedand this application filed February 20, 1912, Serial No. 678,912.Renewed March 17,1917. Serial No; 155,618.

To all whom it may concern:

Be it known that We, WILLIAM ARTHUR BONE, of Leeds, in the county ofYork, Eng land, JAMES WILLIAM WILsoN, of Armley, Leeds, in said county,and CYRIL DOUGLAS MoCo'UR'r, of 45 Braxted' Park', Streatham Common,London, S. W., England, subjects of the King of Great Britain, have madecertain new and useful Inventions Relating to Diaphra -Apparatus forBurning Gases, of which the following is a specification, taken inconnection with the accompanying drawing, which forms part of thisapplication, which is based upon and contains subject-matter taken fromour 0.0-" ending United States application Serial 0. 586,058, filedOctober 8, 1910. This invention relates to apparatus for utilizing theaccelerating influence of the 1n-- candes'cent surface of a highlyporous refractory diaphragmupon the' combustion of a suitable explosivemixture of gaseous fuel and air fed in large volume through thediaphragm toward its heated outer surface, so that a-largefproportion'of the .potentlal energy of the fuel is liberated asradiant energy from theincandescent surfaceso as to be available inconnection with many Industrial gas heating operations. When an. ex-.plosive mixture of coal gas and air, for 1n stance, in their combiningproportions .or with air in slight excess thereof is passed at suitableveloclty, or suitable quantity, through the pores or interstices of asuitable porous refractory diaphragm into its incandescent surface layera highly accelerated and substantially fiameless combustion of the gastakes place within the interstices,

pores or parts of the incandescent diaphragm layer which aremore or less1m-.

pregnated or in-contact with the'gaseous;

mixture; and ener thus developed in large amounts by this intensified,complete and eflicient combustion is absorbed by 'theadjacent surfacelayer of the diai hragm and maintains it in a state of incandescencethus securing a very convenient and efiicient source ofradiant energy.This highly-accelerated, or intensified surface combustion seems to bet6 the emission of char ed corpuscles ore'isctrons from such incanescent solids, and the consequent formation of,

layers of electrified or ionized gas in which the temperature attainablein any particupressure an phragm unit.

the chemical changes incident to combustion proceed with extraordinaryrapidity. It has been demonstrated that the incandescent solid plays anactive and important part in I the combustion of the explosive gaseousmix* ture under these conditions, the particles of the incandescentsolid apparently forming a composite system with the adjacentmolecombustible vapors, natural gas and mix-' tures thereof, all ofwhich are hereinafter referred toas combustible gases, although lar caseWill naturally depend upon the calorific intensity of the gaseousmaterial employed. The combustible gas is combined with air orotheravailable supporter of-combustion in preferably substantially the.combimng proportions or with'a slight excess or' deficiency of air,although the proportions of the constituent gaseous materials may varyconsiderably and still's'ecure an explosive gaseousmixture, such as iscapable of explosive combustion or inflammation, possibl underconditions of increased temperature. 7

In the illustrative embodi-'me n'ts of this inventionshown in thedrawings in a somewhat diagrammatic way,-

v Figure 1 is a vertical central section through a form of diaphragmapparatus.

Fig. 2 is a similarvlew through a pair of; opposed diaphragms, r

Fig: 3 is a similar view showing-an inverted convex diaphragm inconnectionwith a hood and flue. v

Fig. 4; shows in section a tubular dia- Fig. 5, is a" diagrammatic viewshowing a magnified'section of the diaphragm structure;and I Fig. 6 issimilar view showing diagram; matically one of thechannels in'suchporous 1 diaphragrns.

'cules of the combining gases, so that such I The porous refractorydiaphragm may be given any suitable shape so as to have the desired formof incandescent outer surface from which the heat is transmitted. In theillustrative form of diaphragm unit shown in Fig. 1 the porous andpermeable diaphragm 1 may be in the form of a flat plate of suflicientlyrefractory material preferably formed of. agglomerated or unitedparticles or grains of substantially uniform size so as to form tortuouschannels for the passage of the explosive gaseous mixture through thediaphragm. The diaphragm which may be an inch or so thick may be mountedin any desired way, as for instance, by being supported in a suitablecasing 2 of iron or other suitable material which -may be formed with asuitable recess behind the diaphragm communicating with the injectingpipe 3 for the explosive gaseous mixture which for example may be formedby forcing the combustible gas through the inlet pipe 6 in the desiredamounts controlled by the gas valve 7 while air is similarly suppliedunder the desired pressure through the air inlet pipe 1 to the extentdetermined by the adjustment of the air valve 5. In order to keep theedge of the diaphragm cool it is desirable to minimize the discharge ofgas from this part of the outer or discharge surface 8 of the diaphragmin any suitable way, as for instance 'applying a suitable imperviouscoating 11 to the edge and adjacent inner face of the diaphragm. Asuitable impervious coating for this purpose may be formed of a mixtureof finely ground burned fireclay and sodium silicate which may beapplied in moistened condition and then warmed sufficiently to causesetting of this cement-like material which forms a hard materialsomewhat like Portland cement or limestone. plaster of Paris or otherimpervious cementlike material may also be used for this imperviouscoating or the desired part of-the diaphragm, may be rendered imperviousby a suitable glaze formed during its manufacture. The diaphragm ispreferably mounted within a suitable seat 10 in the casing of such shapeas to substantially conform to the edge of the diaphragm which ispreferably located so as to be protected by the edge or flange 9 of thecasing. Any suitable cement or luting material, as shown at 12, may beused to hold the diaphragm within the casing, as for instance, fire-clayor preferably a mixture of finely ground burned fire-clay and sodiumsilicate which may be caused to set by suitable warming, or othersuitable cementitious material, such as plaster of Paris, asbestos'spasse, or whitelead compositions may be use Such incandescent diaphragmsmay be arranged horizontally, vertically or at any.

cated in Fig. 2 the incandescent diaphra'gms' l5 and 16 are placed atany suitable distance apart so as to heat both sides of the articleplaced between them. The diaphragm 15 may be mounted within a suitablecasing 17 connecting with the injecting pipe 18 and formed with asuitably connected support, if desired. The opposing diaphragm 16 may bemounted in a similar support 19 .having the injecting pipe .20.

In some cases instead of using plain diaphragms many other special formsor contours suited to special purposes may be used, such, for example,as the dome-shaped or convex diaphragm shown in Fig. 3. In this case theporous refractory diaphragm 21 is shown mounted in inverted position inthe iron or other suitable casing 22 so as to have the outer hot surfaceof the diaphragm pointed downward so as to be suitable, for instance,for heating a room when mounted in its upper portionor for heating orevaporating liquids or other material placed beneath the diaphragm. Asindicated, the diaphragm and its connected casing may in thisinstance beconveniently supported by the injecting pipe 23 for explosive gaseousmixture, and if desired a suitable hood 24 may be mountedin connectionwith the diaphragm so as to carry oil the products of combustiontherefrom in connection with a suitable flue, such as 25. A form oftubular diaphragm 26 is shown in Fig. 4 as mounted within a suitablecasing or support 27 of iron or other suitable material so that theexplosive gaseous mixture supplied to the diaphragm through theinjecting pipe 28 maintains the outer surface of the porous diaphragm inincandescent condition. The explosive gaseous mixture may be formed andfed to any such refractory diaphragms which are sufliciently porous by asuitable injector device in which either the combustible or combustionsupporting constituent may be under pressure and be discharged withsuflicient velocity to draw in and mix the other component of theexplosive mixture and feed the same with sufficient pressure through thediaphragm.

In Fig. 4 the injector device may as indicated comprise the curvedinjector throat 29 with which the injector nozzle 31 cooperates so as todraw in additional gaseous material through the annular passage 32 thesize of which may be regulated by adjusting theposition of the valve 34threaded or otherwise adjustably mounted on the nozzle, for instance.The supporting casing 33 communicating with a suitably valved supplypipe may be used to connect the injector throat with the pipe 30communicating with the nozzle sons to allow the entrance of air or othergaseous supporter of combustion around the nozzle when the combustiblegas is discharged therefrom at a velocity pressure of a few pounds persquare inch which is sufficient to produce a pressure behind thediaphragm of an eighth or a quarter of an inch of water or more.

The valve in thegas supply pipe may be used to regulate the amount ofgas discharged from the injecting nozzle and the valve indicated in theair supply pipe may regulate the amount of air drawn in.

These refractory diaphragms .of a high and quite uniform degree ofporosity may bemanufactured in a number of ways, as for instance, bysuitably uniting refractory porous granules of substantially uniformsize so as to give a high degree of porosity and permeability to thediaphragm'which is penetrated by tortuous gas passages formed by thenetwork of spaces or interstices between the refractory particles orgrains of which the diaphragm is made up. Porous fireclay is asatisfactory material for such diaphragms and may be readily crushed orground in any desired way into particles or grains ofthe desired size.The granules for making any particular class of diaphragms 5 aresubstantially uniformly sized, that is,

for instance, the granules passing a sieve having 30 meshes to thelinear inch are selected and freed from objectionable fine material byseparating therefrom all particles which will pass a -mesh sieve.Another size of granules useful for such diaphragms for less explosivegaseous mixtures are those passing a lfi-mesh sieve and retained by a32-mesh sieve. Still larger sized granules, such as are suitable formaking diaphragms which may be generally used for burning coal gas andilluminating gas are those passing an S-m'esh sieve and retained by a16- me'sh sieve. These porous granules may be united in any desired waypreferably by means which will not destroy or undesirably impair theporosity of each of the granules. This may be accomplished by the use ofsuitable binding agents, as by incorporating with the. granules a smallpercentage of feldspar or a mixture of feldspar with a little fluosparto the extent of ten per cent. or so of the granules. Such bindingmaterial in dry finely powdered form may be incorporated withthegranules by first wetting them and then thoroughly stirring them withthe dry binding material which thereby coats the particles which maythen be ims.

mediately molded while in this moistened coated condition. The moldeddiaphragms are then burned at a high temperature in a suitable potterykiln orother furnace so that,

the temperature is carried considerably beyond the fusing point of thebinding material and this causes the binding material.sufiicientlyrigidly held in position. For ina stance, diaphragms may beburned at temperatures of 1300 to 1400 degrees C. and operated attemperatures of 800 or 900 degrees C. with good results. It is alsodesirable to carefully mold these diaphragms so as to prevent thedestruction of the tortuous passages which naturallv form between therough granules and for this reason moistened material is preferably onlycompacted very slightly as with an ordinary rolling pin in molding thediaphragms and it is for some purposes even better to merely remove thesurplus material supplied to the diaphragm molds so as to prevent anypossibility of crushing the particles or'undesirably packing them. It isalso desirable to remove the surface of the baked diaphragms where theparticles have become alinedasby being in contact with the smooth moldsurface and this may be done in any desired way as with a rasp beforethey are used. For some purposes also it 1s not desirable to use as thedischarge or outer active surface of the diaphragms the surface whichhas been in contact with the mold,butto use thissurface for the innersurface through which the gas enters. In this way. diaphragms may beformed of extremely high and uniform porosity, the degree of po-'rosity, that is, the proportion of porous cavities and spaces betweenthe particles 'or granules being as high as 50 per cent. or

. so in some cases. For some special purposes t is sometimes deslrableto form the (1111-.

phragms with outer discharge surfaces of coarser partlcles and withbodles or inner layers of finer particles which can of coursebe'conveniently effected when molding the moist material.

"The substantially uniform size of the granules and the tortuous natureof the gas passages between them are especially desirable in highlypermeable diaphragms suit able for operation under low gas pressures.

The size of the granules and consequent size of gas passages andpermeability of diaphragms of this character should be so chosen as togive the proper operation with the particular kind of gas with whichtheyare tobe used, the size of granules being in all cases small enough sothat together with the tortuous character of the gas passages and thegreatly increased cooling effect due to the impinging action and roughsurfaces of the granules forming these passages,

flashbackthrough the diaphragm passages is greatly minimized andpractically eliminated under operating conditions with the particularexplosive gaseous mixtures used. Diaphragms an inch and a quarter or sothick may be formed in this way of porous fireclay granules of betweenone-eighth and one-sixteenth inch mesh, which give good results withexplosive coal gas and air mixtures supplied under pressures of aboutoneeighth of an inch of water, and such diaphragms may burn as much as 75 cubic feet or so of coal gas or 400 to 500 cubic feet of explosivecoal gas and air mixture per hour for every square foot of diaphragmsurface, thus maintaining the outer heated surface of the diaphragm'at atemperature of about 850? C. or so under freely radiating condi tionsl;A diaphragm similarly formed of granules of substantially sixteen-meshsize will burn a similar amount of explosive coal 50 mesh or even ofstill finer granules of between 50 and 100 mesh size in the case of moreinflammable water gas mixtures.

The action of such porous refractory diaphragms in eflecting theaccelerated surface combustion of explosive mixtures can be understoodby reference to Fig. 5 which diagrammatically illustrates the diaphragmstructure on a greatly magnified scale. The outer granules or particles40 of porous refractory material are the ones maintained in a highlyheated or incandescent condition by the combustion of the explosivegaseous mixtures injected against them so as to maintain'them in thishighly heated condition in which they can radiate heat to each other andfrom the exposed outer surface of the diaphragm. As may be seen byreference to the portion of these granules within the plane of thissection the granules not only have rough outer surfaces, but haveinternal pores such as 42 communicating in many instances with the outersurfaces to form cavities which the gases may readily penetrate. Theseparticles and the similar inner particles 41 are firmly united, but".have between them relatively large cavities or interstices 43, so thatthe entire diaphragm is formed with a network cit-concatenation of thesecommunicating spaces or channels. Fig. 6 illustrates diagrammaticallythe character of one of these tortuous gas passages or channels 44through a diaphragm of this character, the section being taken along theirregular line following the greatest crosssection of this particularchannel through the porous particles. These same factors promote thesurface combustion action occurring in the hot outer layer of the'diaphragm several granules thick. The explosive gases are here brought.into impingement with the rough incandescent surfaces of the granules sothat penetration and contact with the gas is greatly promoted and thehighly accelerated combustion takes place much more effectively thanwould be possible in the case of a dense porcelain plate, for example,drilled with separate small holes.

For the proper operation of these diaphragms it seems desirable ornecessary to have sufiiciently free radiation or dissipation of-the heatfrom the incandescent outer diaphragm layer to prevent the accumulationof heat in this layer to such an extent that it can undesirably heat byconduction the rearward layers of the diaphragm and thus cause the zoneof surface combustion of the explosive gases to slowly and progressivelymove back away from the outer surface. This back heating action occurswhen, for example, two coal gas diaphragms are arranged with theirincandescent surfaces close together, or when a refractory nonconductingplate or the like is moved against or close to a hot diaphragm, and mayalso take place when excessive amounts of the gaseous mixtures are beingburned in the diaphragm so that the heat developed exceeds that whichcan be properly dissipated from the radiating diaphragm surface orotherwise. at the relatively moderate incandescent temperatures at whichit seems preferable to operate these diaphragms.

When such back heating takes place the outer diaphragm surface actuallyfrequently cools as after the combustion zone or incandescent layer hasmoved backward into the diaphragm, and instead of a substantiallyuniform incandescent surface darker spots appear and in many instancesthe outer surface cools below a bright heat when the combustion layerhas retreated some distance. When this slow retrogression or penetrationof the hot combustion zone through the diaphragm occurs the explosivegases in the diaphragm chamber may become ignited, and it is of coursedesirable to quickly correct this undesirable action as by shuttingoifthe gas supply and cooling the diaphragm or by considerablyincreasing the proportion of air mixed with the combustible gas suppliedso that normal conditions are restored. Then the relatively freerradiation of heat from the incandescent diaphragm surface should beinsured so as to cause the heat to be radiated and dissipated as fast asit is generated by surface combustion, and prevent the progressiveaccumulation of heat and rise of temperature in the incandescent surfacelayer which undesirably heats the adjacent material and initiates suchbackheating. In normal operation of such refractory diaphragms theexplosive gaseous mixture continues to burn with accelerated surfacecombustion in the incandescent surface-layer and this combustion may bedefinitely localized and maintained at the desired intensity byregulating the supply of explosive gases and the amount of heatradiation as by increasing or diminishing the freedom of radiation, so

tem. This back heatin as to insure equilibrium and counteract anyunbalancing tendencies in the heating sysaction is distinct from theordinary bac flashing or quick backfiring of explosive gaseous mixturesin tubes, such backfirin action being suppressed or eliminated inthe'diaphragms of the present inventionby the greatly increased coolingeffect on the gases of the small granules and the relatively largesurface of the tortuous gas passages there- 'through, For instance, inthe coal gas dia- ,phragms referred to having granules of betweenone-eighth and one-sixteenth inch mesh, the passages are of appreciablesize and the porosity is so great that the total area of the passagesthrou h the diaphragm is in the neighborhood 0 30 to square inches foreach square foot of diaphragm surface. But nevertheless, no backfiringoccurs with. a properly made diaphragm of this character, and theimportance of the tortuous roughened character of the gas passages inpreventing backfiashing can be appreciated from the fact that only asmuch gas will pass through 'a square foot diaphragm of this character aswill issue from an orifice or nozzle about one-quarter or one-half inchin diameter under e ual pres sures. In gradually shutting o the gassupply to diaphragms of this character the speed of the explosivemixture passing through the' tortuous channels of the diaphragm "isgradually reduced to zero, but

the cooling action of the diaphragm structure is such as to preventbackiiashing of the explosive gases n contact w1th the incandescentouter face ofzthe diaphragm even under these conditions.

It is of course understood that many other refractory substances such asmagnesia,

bauxite, ganister, preferably those having a suificiently porouscharacter may be used to form the granules which may be-united in manyways to formporous diaphragms of this character. Various firebrick'compositions have proved highly desirable, especially the more of thischaracter.

Having described the invention in connection with a number ofillustrative em:

bodiments, arrangements, proportions, ma terials, pressures, conditions,processes and orders of steps, to the details of which disporousrefractory materials closure the invention is not of course to belimited, what is claimed as new and What is desired to be secured byLetters Patent is set forth in'the appended claims:

1; Apparatus for burning gaseous fuel .comprislng a porous and permeablerefractory diaphragm composed of granules'ofre fractory material bondedtogether to form a network of tortuous-irregular gas passages,

and means for maintaining a supply of an explosive gaseous mixtureagainst one face of the diaphragm whereby the mixture will be caused toflow through the tortuous pas-' the diap ragm whereby the mixture willbe caused to flow through the tortuous passages of the dia hra to causeaccelerated substantially ame ess combustion to take place within theouter layer of the diaphra when the latter becomeshighly heated, and

means for preventing the entrance of the explosive gaseousmixture' intothe outer edge portions of'the diaphragm to prevent said portions frombecoming highly heated.

3. In an apparatus for burning gaseous fuel, a fporousrefractorydiaphragm composed o fire clay granules united by a relativelyfusible material'to form a network of tortuousv irregular gas passages,a casing within which the diaphragm is mounted, an

impervious cement connecting the edge of said diaphragm with saidcasing, and means to feed an explosive gaseous mixture through saidcasing to said diaphragm, the burning of the ex losive mixture causinthe outer face of t e diaphragm to be eated and thereby producing aflameless combustion within the outer layer of the diaphragm.

.' 4. In an apparatus for burning gaseous porous refractory diaphragmcomfuel, a

posedo granules of refractor material united by relatively fusiblematerial to form a network of tortuous irregular gas passages, a casingwithin which the diaphragm is mounted, an impervious cement connectingthe edge of said diaphragm with said casing, and means to feed anexplosive gaseous mixture through said casing to said diaphragm, theburning ofthe explosive mixture causing the outer face of the diaphragmto be heated and thereby producing a substantially flameless combustionwithin the outer layer of the diaphragm.

5. Apparatus for burning gaseous fuel, comprising a porous and permeablerefractory diaphragm composed of granules of refractory material ofsubstantially uniform size bonded together to form a network of tortuousirregular gas passages, and means for maintaining a supply of anexplosive gaseous mixture against one face of the diaphragm whereby themixture will be caused to flow through the tortuous passages of thediaphragm to cause accelerated substantially flameless combustion totake place 'within the outer layer of the diaphragm when the latterbecomes highly heated, the said tortuous passages of the diaphragm beingof a size to prevent back-flashing of the explosive gaseous mixturetheretllrough, and th( diaphragm having a rough outer surface.

WVILLIAM ARTHUR BONE. JAMES WILLIAM WVILSON. CYRIL DOUGLAS MCCOURT.

Witnesses:

P. G. ALExANDuE, CHARLES E. TAYLOR.

